package helper;
import java.security.*;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
/** 
 * 字符串工具集合 
 * @author Liudong 
 */
public class DESHelper {
	private static final String PASSWORD_CRYPT_KEY = "__~1aX&*";
	private final static String DES = "DES";
	/** 
	 * 加密 
	 * @param src 数据源 
	 * @param key 密钥，长度必须是8的倍数 
	 * @return  返回加密后的数据 
	 * @throws Exception 
	 */
	public static byte[] encrypt(byte[] src, byte[] key) throws Exception {
		//DES算法要求有一个可信任的随机数源 
		SecureRandom sr = new SecureRandom();
		// 从原始密匙数据创建DESKeySpec对象 
		DESKeySpec dks = new DESKeySpec(key);
		// 创建一个密匙工厂，然后用它把DESKeySpec转换成 
		// 一个SecretKey对象 
		SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
		SecretKey securekey = keyFactory.generateSecret(dks);
		// Cipher对象实际完成加密操作 
		Cipher cipher = Cipher.getInstance(DES);
		// 用密匙初始化Cipher对象 
		cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);
		// 现在，获取数据并加密 
		// 正式执行加密操作 
		return cipher.doFinal(src);
	}
	/** 
	 * 解密 
	 * @param src 数据源 
	 * @param key 密钥，长度必须是8的倍数 
	 * @return   返回解密后的原始数据 
	 * @throws Exception 
	 */
	public static byte[] decrypt(byte[] src, byte[] key) throws Exception {
		// DES算法要求有一个可信任的随机数源 
		SecureRandom sr = new SecureRandom();
		// 从原始密匙数据创建一个DESKeySpec对象 
		DESKeySpec dks = new DESKeySpec(key);
		// 创建一个密匙工厂，然后用它把DESKeySpec对象转换成 
		// 一个SecretKey对象 
		SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
		SecretKey securekey = keyFactory.generateSecret(dks);
		// Cipher对象实际完成解密操作 
		Cipher cipher = Cipher.getInstance(DES);
		// 用密匙初始化Cipher对象 
		cipher.init(Cipher.DECRYPT_MODE, securekey, sr);
		// 现在，获取数据并解密 
		// 正式执行解密操作 
		return cipher.doFinal(src);
	}
	/** 
	 * 密码解密 
	 * @param data 
	 * @return 
	 * @throws Exception 
	 */
	public final static String decrypt(String data) {
		try {
			return new String(decrypt(hex2byte(data.getBytes()),
			PASSWORD_CRYPT_KEY.getBytes()));
		} catch (Exception e) {
		}
		return null;
	}
	/** 
	 * 密码加密 
	 * @param password 
	 * @return 
	 * @throws Exception 
	 */
	public final static String encrypt(String password) {
		try {
			return byte2hex(encrypt(password.getBytes(), PASSWORD_CRYPT_KEY
				.getBytes()));
		} catch (Exception e) {
		}
		return null;
	}
	/** 
	 * 二行制转字符串 
	 * @param b 
	 * @return 
	 */
	public static String byte2hex(byte[] b) {
		String hs = "";
		String stmp = "";
		for (int n = 0; n < b.length; n++) {
			stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
			if (stmp.length() == 1)
				hs = hs + "0" + stmp;
			else
				hs = hs + stmp;
		}
		return hs.toUpperCase();
	}
	
	public static byte[] hex2byte(byte[] b) {
		if ((b.length % 2) != 0)
			throw new IllegalArgumentException("长度不是偶数");
		byte[] b2 = new byte[b.length / 2];
		for (int n = 0; n < b.length; n += 2) {
			String item = new String(b, n, 2);
			b2[n / 2] = (byte) Integer.parseInt(item, 16);
		}
		return b2;
	}
	public static void main(String[] args) {
		String str = "123";
		String nstr = DESHelper.encrypt(str);
		String ostr = DESHelper.decrypt(nstr);
		System.out.println(nstr + ":" + ostr);
		
	}
}